1. Field of the Invention
This invention relates broadly to systems and methods for treating an artery or vein of a patient. More particularly, this invention relates to systems and methods for treating blood clots and atherosclerosis in the brain and peripheral vessels of a patient, although it is not limited thereto.
2. State of the Art
A stroke is caused by a rupture or an occlusion of a blood vessel which leads to oxygen deprivation in the brain. In the United States, nearly eight hundred thousand people suffer a stroke each year, and over one hundred and forty thousand people die from strokes each year. Stroke is the leading cause of serious, long-term disability in the United States and the third leading cause of death. Approximately three-quarters of strokes in the United States are first attacks and approximately one-quarter are recurrent attacks. Eighty seven percent are ischemic in nature, meaning that they are caused by a restriction, obstruction, or blockage in the blood supply of the patient, and thirteen percent are hemorrhagic, meaning that they are caused by excessive bleeding. The economic cost of stroke to the United States is over forty billion dollars per year. The direct costs of medical care and therapy are almost thirty billion dollars per year.
It is well known in the art that the extent to which treatment of a stroke is successful in preventing death and/or in reducing the consequent damage to a patient is largely influenced by the time that elapses between the onset of the stroke and the proper treatment of the stroke. The elapsed time is a function of not only whether or not a patient is able to get to a medical facility or hospital, but also the nature of the stroke and whether or not the particular medical facility or hospital to which the patient is initially brought is best equipped to treat the stroke. The capability of the medical facility to treat the particular stroke may not be known until the patient is properly evaluated and analyzed. Generally, if more than three hours elapse between the onset of the stroke and treatment, then a combination of tPA (Tissue Plasminogen Activator—a drug used to dissolve blood clots) and mechanical treatments need to be utilized.
If a cerebral clot is diagnosed and removed within four hours of the clot's formation, a patient generally has a better chance to recover fully. If a neurointerventionist happens to be present (most are generally located at stroke centers), then certain devices may be available to remove the cerebral clot. One device is the Merci retrieval device made by Concentric Medical. With the Merci device, a small catheter (e.g., having a 0.015″ inner diameter) is advanced through the femoral artery and fed up to the brain. A special Nitinol wire is advanced through the catheter to the clot. The wire changes form after passing through the clot and can be used to pull out the clot. A second device, sold by Penumbra, Inc. also uses a small catheter which is advanced through the femoral artery and fed up to the brain, but instead of pulling the clot out mechanically, utilizes suction to pull out the clot. Both of these devices are often unsuccessful in their intended functions.
Peripheral vascular disease (PVD) is a slow and progressive circulation disorder. It may involve disease in any of the blood vessels outside of the heart and diseases of the lymph vessels—the arteries, veins or lymphatic vessels. Organs supplied by these vessels such as the brain, heart, and legs, may not receive adequate blood flow for ordinary function. However, the legs and feet are most commonly affected; thus the name peripheral vascular disease. PVD includes a group of diseases in which blood vessels become restricted or blocked.
Venous thrombosis is the term used to describe a blood clot (thrombus) in a vein of the body. Most commonly these thrombi are found in the veins of the lower extremities. Thrombi found in veins deep in thighs or calves give rise to a condition called “deep vein thrombosis” (DVT). Venous thrombosis can occur in healthy as well as sick individuals. A complication most commonly associated with venous thrombosis is the condition known as “pulmonary embolism.” A pulmonary embolus is actually a clot that has broken free from a vein wall and has traveled to the pulmonary artery, and then, if not removed, to a lung. When an embolus blocks a blood vessel in the lung, breathing is compromised and death may ensue. Accordingly, early treatment of DVT is desirable.
Other conditions associated with PVD that affect the veins include varicose veins, and chronic venous insufficiency. Lymphedema is an example of PVD that affects the lymphatic vessels. PVD is a progressive disease that can lead to gangrene of the affected area. PVD may also occur suddenly if an embolism occurs or when a blood clot rapidly develops in a blood vessel already restricted by an atherosclerotic plaque, and the blood flow is quickly cut off.
Various medical procedures or surgeries are recommended treatments for treating atherosclerosis and blood clots in peripheral vessels of a patient. But current treatments for relatively smaller vessels having atherosclerosis and/or blood clots are limited. These treatments may include angioplasty and vascular surgery.